1. Field of the Invention
The present invention relates to an electric torque converter used in an automatic transmission and mounted on a hybrid vehicle employing a parallel hybrid system, using both an internal combustion engine and an electric motor (an electric motor generator) for vehicle propulsion.
2. Description of the Prior Art
In recent years, it is strongly desired to improve fuel economy of automotive vehicles, for the purpose of protecting global atmospheric and saving earth resources. In order to reduce fuel consumption, there have been proposed and developed various hybrid vehicles. Hybrid vehicles in which an internal combustion engine and an electric motor (an electric motor/generator), both serving as a propelling power source, are arranged in series to each other or in parallel with each other, and operate at various running modes, such as a motor-propelled vehicle driving mode, an engine-propelled vehicle driving mode, a regenerative mode, a power-assist mode, an electric power generation mode, and the like. For example, during the power-assist mode, the engine (a primary power source) is assisted by the electric motor (a secondary power source). Also, when the hybrid vehicle is decelerating, the hybrid system operates at the regenerative mode during which the electric motor is employed to convert kinetic energy of the vehicle into electric energy and to regenerate electricity which is stored in a car battery. One such parallel hybrid system has been disclosed in Japanese Patent Provisional Publication No. 9-226392. FIG. 4 shows a development cross-sectional view of the parallel hybrid system disclosed in the Japanese Patent Provisional Publication No. 9-226392. As shown in FIG. 4, rotational motion of a crankshaft of an internal combustion engine is input into a composition/distribution mechanism 103 capable of mechanically combining two different forces, that is, torque produced by the engine and torque produced by the motor/generator, with each other, and of mechanically distributing the torque produced by the engine properly. Electricity is generated by rotating a first motor generator 102 (mainly serving as an electric generator) connected to the composition/distribution mechanism 103. During the power assist mode (or the torque assist mode) or during the motor-propelled vehicle driving mode, torque (driving force) produced by a second motor generator 101 (mainly serving as an electric motor) is input into the composition/distribution mechanism 103. During vehicle deceleration, the first motor generator 102 also functions to regenerate braking energy (electricity) which is stored in the battery. The electricity regenerated and stored in the car battery can be reused for the torque-assist operating mode or the motor-propelled vehicle driving mode.
In order to efficiently travel the hybrid vehicle, it is necessary to accurately recognize or detect vehicle operating conditions such as a vehicle traveling state, and to select or use the power source suitable for the vehicle traveling state recognized, or to execute efficiently the electric power generation mode or the regenerative mode. For the reasons set forth above, it is important to achieve accurate motor generator rotation control (i.e., accurate motor generator rotational speed control). As information needed for the motor generator rotation control, input information from a revolution sensor (or a rotational position sensor) is often used. In the hybrid system as disclosed in the Japanese Patent Provisional Publication No. 9-226392, a resolver 105 is provided for detecting the rotational position (rotor angle) of the first motor generator 102 (mainly serving as the generator), while a resolver 104 is provided for detecting the rotational position (rotor angle) of the second motor generator 101 (mainly serving as the motor). The basic principle of each of the resolvers 104 and 105 is similar to that of an electric motor. That is, the rotational position of the motor generator is sensed or detected by monitoring or reading an electromotive force produced by rotation of the motor generator rotor.
However, in the parallel hybrid system disclosed shown in FIG. 4, the resolver 105 for the first motor generator 102 is arranged in close proximity to a stator coil of the first motor generator 102, and also part of flux of magnetic force produced by the stator coil tends to undesiredly spread or escape in the transverse direction of the stator coil. Therefore, the accuracy that detects the rotational position of the first motor generator resolver 105 is lowered owing to the magnetic flux partially spreading in the transverse direction. Regarding the second motor generator resolver 104, the resolver is accommodated in a resolver chamber separated from a motor generator chamber for the second motor generator 101 to prevent the resolver 104 from being affected by electromagnetic wave noise produced by the motor generator 101. Thus, a resolver cover for the resolver 104 must be individually installed or mounted on the motor housing of the motor generator 101, thereby increasing the number of parts of the system, and thus resulting in an increased man-hour for installation of the resolver on the motor housing.
Accordingly, it is an object of the invention to provide an electric torque converter mounted on a parallel hybrid vehicle, which avoids the aforementioned disadvantages of the prior art.
It is another object of the invention to provide an electric torque converter mounted on a parallel hybrid vehicle employing a parallel hybrid system, which can accurately detect the rotational position of an electric motor generator (electric motor/generator) by means of a resolver, while preventing the resolver from being affected by undesirable electromagnetic wave noise produced by a stator coil of the motor generator.
In order to accomplish the aforementioned and other objects of the present invention, an electric torque converter mounted on a parallel hybrid vehicle employing a parallel hybrid system, using both an internal combustion engine and an electric motor for propulsion, said electric torque converter comprises an electric motor generator having a motor generator rotor and a motor generator stator coil, a composition-and-distribution mechanism adapted to be located between the engine and a transmission for mechanically combining torque produced by the engine and torque produced by the motor generator with each other and for mechanically distributing the torque produced by the engine into the motor generator and a transmission input shaft of the transmission, the composition-and-distribution mechanism having a rotating member arranged coaxially with the transmission input shaft, a converter case which comprises a casing member formed with a boss portion supporting the rotating member of the composition-and-distribution mechanism by a bearing member, and partitioning the motor generator from the composition-and-distribution mechanism, a rotor support which comprises a substantially cylindrical outer support portion supporting thereon the motor generator rotor, a substantially cylindrical inner support portion whose inner periphery is fixedly connected to the rotating member, and a connection portion interconnecting the substantially cylindrical outer support portion and the substantially cylindrical inner support portion, a locknut located on an outer periphery of the rotating member and mating with a first one of axial ends of the substantially cylindrical inner support portion of the rotor support, for pre-loading the bearing member via the rotor support, and a position sensor which comprises a resolver rotor located on an inner periphery of the substantially cylindrical outer support portion, and a resolver stator located on an outer periphery of the boss portion of the casing member. It is preferable that the substantially cylindrical inner support portion of the rotor support has internal splines, and the rotating member has external splines formed on the outer periphery thereof, and that spline-connection between the internal splines and the external splines is established by screwing the locknut onto the external thread portion of the rotating member so that the locknut is tightened up onto the first axial end of the substantially cylindrical inner support portion of the rotor support, and that the second axial end of the substantially cylindrical inner support portion is abutted-engagement with the inner race of the bearing member while applying pre-load to the bearing member. More preferably, the electric torque converter may further comprise a torque converter input shaft arranged coaxially with the transmission input shaft, and also the rotor support, the motor generator, and the position sensor are arranged concentrically with the torque converter input shaft, so that the motor generator rotor is located on the outer periphery of the substantially cylindrical outer support portion of the rotor support, and that the motor generator stator coil is radially spaced apart from the resolver rotor via the motor generator rotor.